.\" $OpenBSD: X509_new.3,v 1.45 2024/09/02 08:04:32 tb Exp $
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.Dd $Mdocdate: September 2 2024 $
.Dt X509_NEW 3
.Os
.Sh NAME
.Nm X509_new ,
.Nm X509_dup ,
.Nm X509_REQ_to_X509 ,
.Nm X509_free ,
.Nm X509_up_ref ,
.Nm X509_chain_up_ref
.Nd X.509 certificate object
.Sh SYNOPSIS
.In openssl/x509.h
.Ft X509 *
.Fn X509_new void
.Ft X509 *
.Fo X509_dup
.Fa "X509 *a"
.Fc
.Ft X509 *
.Fo X509_REQ_to_X509
.Fa "X509_REQ *req"
.Fa "int days"
.Fa "EVP_PKEY *pkey"
.Fc
.Ft void
.Fo X509_free
.Fa "X509 *a"
.Fc
.Ft int
.Fo X509_up_ref
.Fa "X509 *a"
.Fc
.Ft STACK_OF(X509) *
.Fo X509_chain_up_ref
.Fa "STACK_OF(X509) *chain"
.Fc
.Sh DESCRIPTION
.Fn X509_new
allocates and initializes an empty
.Vt X509
object with reference count 1.
It represents an ASN.1
.Vt Certificate
structure defined in RFC 5280 section 4.1.
It can hold a public key together with information about the person,
organization, device, or function the associated private key belongs to.
.Pp
.Fn X509_dup
creates a deep copy of
.Fa a
using
.Xr ASN1_item_dup 3 ,
setting the reference count of the copy to 1.
.Pp
.Fn X509_REQ_to_X509
allocates a new certificate object, copies the public key from
.Fa req
into it, copies the subject name of
.Fa req
to both the subject and issuer names of the new certificate, sets the
.Fa notBefore
field to the current time and the
.Fa notAfter
field to the given number of
.Fa days
in the future, and signs the new certificate with
.Xr X509_sign 3
using
.Fa pkey
and the MD5 algorithm.
If
.Fa req
contains at least one attribute,
the version of the new certificate is set to 2.
.Pp
.Fn X509_free
decrements the reference count of the
.Vt X509
structure
.Fa a
and frees it up if the reference count reaches 0.
If
.Fa a
is a
.Dv NULL
pointer, no action occurs.
.Pp
.Fn X509_up_ref
increments the reference count of
.Fa a
by 1.
This function is useful if a certificate structure is being used
by several different operations each of which will free it up after
use: this avoids the need to duplicate the entire certificate
structure.
.Pp
.Fn X509_chain_up_ref
performs a shallow copy of the given
.Fa chain
using
.Fn sk_X509_dup
and increments the reference count of each contained certificate
by 1.
Its purpose is similar to
.Fn X509_up_ref :
The returned chain persists after the original is freed.
.Sh RETURN VALUES
.Fn X509_new ,
.Fn X509_dup ,
and
.Fn X509_REQ_to_X509
return a pointer to the newly allocated object or
.Dv NULL
if an error occurs; an error code can be obtained by
.Xr ERR_get_error 3 .
.Pp
.Fn X509_up_ref
returns 1 for success or 0 for failure.
.Pp
.Fn X509_chain_up_ref
returns the copy of the
.Fa chain
or
.Dv NULL
if an error occurs.
.Sh SEE ALSO
.Xr ASIdentifiers_new 3 ,
.Xr ASRange_new 3 ,
.Xr AUTHORITY_KEYID_new 3 ,
.Xr BASIC_CONSTRAINTS_new 3 ,
.Xr crypto 3 ,
.Xr d2i_X509 3 ,
.Xr IPAddressRange_new 3 ,
.Xr PKCS8_PRIV_KEY_INFO_new 3 ,
.Xr X509_ALGOR_new 3 ,
.Xr X509_ATTRIBUTE_new 3 ,
.Xr X509_check_ca 3 ,
.Xr X509_check_host 3 ,
.Xr X509_check_issued 3 ,
.Xr X509_check_private_key 3 ,
.Xr X509_check_purpose 3 ,
.Xr X509_CINF_new 3 ,
.Xr X509_cmp 3 ,
.Xr X509_CRL_new 3 ,
.Xr X509_digest 3 ,
.Xr X509_EXTENSION_new 3 ,
.Xr X509_find_by_subject 3 ,
.Xr X509_get0_notBefore 3 ,
.Xr X509_get0_signature 3 ,
.Xr X509_get1_email 3 ,
.Xr X509_get_ex_new_index 3 ,
.Xr X509_get_extension_flags 3 ,
.Xr X509_get_pubkey 3 ,
.Xr X509_get_pubkey_parameters 3 ,
.Xr X509_get_serialNumber 3 ,
.Xr X509_get_subject_name 3 ,
.Xr X509_get_version 3 ,
.Xr X509_INFO_new 3 ,
.Xr X509_load_cert_file 3 ,
.Xr X509_LOOKUP_hash_dir 3 ,
.Xr X509_LOOKUP_new 3 ,
.Xr X509_NAME_new 3 ,
.Xr X509_OBJECT_new 3 ,
.Xr X509_PKEY_new 3 ,
.Xr X509_print_ex 3 ,
.Xr X509_PUBKEY_new 3 ,
.Xr X509_PURPOSE_set 3 ,
.Xr X509_REQ_new 3 ,
.Xr X509_SIG_new 3 ,
.Xr X509_sign 3 ,
.Xr X509_STORE_CTX_new 3 ,
.Xr X509_STORE_get_by_subject 3 ,
.Xr X509_STORE_new 3 ,
.Xr X509v3_addr_add_inherit 3 ,
.Xr X509v3_addr_get_range 3 ,
.Xr X509v3_addr_inherits 3 ,
.Xr X509v3_addr_subset 3 ,
.Xr X509v3_addr_validate_path 3 ,
.Xr X509v3_asid_add_id_or_range 3
.Sh STANDARDS
RFC 5280: Internet X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile
.Sh HISTORY
.Fn X509_new
and
.Fn X509_free
appeared in SSLeay 0.4 or earlier,
.Fn X509_dup
in SSLeay 0.4.4, and
.Fn X509_REQ_to_X509
in SSLeay 0.6.0 .
These functions have been available since
.Ox 2.4 .
.Pp
.Fn X509_up_ref
first appeared in OpenSSL 1.1.0 and has been available since
.Ox 6.1 .
.Pp
.Fn X509_chain_up_ref
first appeared in OpenSSL 1.0.2 and has been available since
.Ox 6.3 .
.Sh BUGS
The X.509 public key infrastructure and its data types contain too
many design bugs to list them.
For lots of examples, see the classic
.Lk https://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt\
 "X.509 Style Guide"
that
.An Peter Gutmann
published in 2000.
